SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Securities Sold Under Agreements to Repurchase (Parenthetical) (Detail) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Securities sold under agreements to repurchase	[1],[2]	$ 300,000	$ 300,000
Callable Repurchase Agreements [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Securities sold under agreements to repurchase		$ 200,000
Maximum [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Assets sold under agreements to repurchase interest rate		3.26%	2.83%
Minimum [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Assets sold under agreements to repurchase interest rate		1.96%	1.96%
Weighted Average [Member] | Callable Repurchase Agreements [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Assets sold under agreements to repurchase interest rate		2.11%

[1] As of September 30, 2017, includes $200 million with an average rate of 2.11% that lenders have the right to call before their contractual maturities at various dates beginning on July 19, 2017. In addition, $100 million is tied to variable rates.

[2] Reported net of securities purchased under agreements to repurchase (reverse repurchase agreements) by counterparty, when applicable, pursuant to ASC 210-20-45-11.